Formulating a fabric care composition at a desirable initial rheology and then maintaining this rheology over the lifetime of the fabric care composition is difficult. In particular, it is difficult to formulate a fabric care composition containing a delivery enhancing agent at a desirable initial rheology and to maintain this rheology over the lifetime of the fabric care product. Delivery enhancing agents are generally polymers that, alone or in combination with other polymers, significantly enhance the deposition of a fabric care benefit agent (e.g., fabric softener active, silicone, perfume) onto the fabric during laundering. It is known that low molecular weight delivery enhancing agents (less than about 2,000,000 Daltons) may cause phase instability. Moreover, high molecular weight delivery enhancing agents may significantly increase the viscosity of fabric care compositions, even when added at low levels.
There have been attempts to improve rheology stability over time in fabric care compositions. For example, the use of unsaturated and/or branched alcohols and fatty acids in certain fabric care compositions to address the problem of thickening of the composition upon storage is known. There have also been attempts to formulate fabric care compositions containing a delivery enhancing agent and various fabric care benefit agents to deliver improved feel and scent benefits. There is a need, however, to formulate a fabric care composition containing a high molecular weight delivery enhancing agent and a fabric care benefit agent at a desirable initial rheology and then to maintain this rheology over the lifetime of the fabric care product.
Importantly, the compositions herein exhibit an improved viscosity, which allows for the addition of desirable polymers. However, polymers that can be used as delivery enhancing agents can thicken the product excessively. Typically, the viscosity of a mix of fabric softening active and target levels of polymer, especially cross-linked polymer, would be too high for an acceptable consumer product. The compositions herein provide both improved performance and a desirable viscosity range.